Machine tool center

ABSTRACT

A machine tool center (10) displays at least one machine tool (11, 12, 13) which has a working area (17) accessible through an operator door (16) to process workpieces (21). Furthermore, a loading/unloading station (14) for the workpieces (21) and a loading device (22) which transports the workpieces (21) between the loading/unloading station (14) and the respective machine tool (11, 12, 13) and changes these at the machine tool (11, 12, 13) are also provided. In the new machine tool center (10) the loading device (22) is arranged below the working space (17) of the machine tool (11, 12, 13) (FIG. 1).

This application is a continuation of U.S. application Ser. No.08/641,508, filed May 1, 1996, now U.S. Pat. No. 5,871,326.

BACKGROUND OF THE INVENTION

The present invention relates to a machine tool center with at least onemachine tool which has a working space accessible through an operatordoor to process workpieces, a loading/unloading station for theworkpieces and a loading device which transports the workpieces betweenthe loading/unloading station and the respective machine tool andchanges these at the machine tool.

1. Field of the Invention

Such machine tool centers are generally known.

2. Related Prior Art

In the known machine tool centers the loading devices are arranged infront of the respective machine tools which are installed alongside oneanother either in a straight line or in a circle. The loading devicedisplays an appliance which moves back and forth between theloading/unloading station and the respective machine tool and herebytransports workpieces. In this way a large number of machine tools canbe loaded by one single loading/unloading station at which theworkpieces to be processed are input and from which the finishedworkpieces are also removed.

The loading device hereby often operates on the same level as theoperator door and changes the workpieces in the machine tool throughthis door. The operator door is, however, simultaneously used for set-upand service work, in other words for maintenance, to change tools, toverify tools or certain geometric factors, etc.

If a fault occurs in one of the machine tools in the known machine toolcenter or service work becomes necessary the respective operator mustreach "past the loading device" through the operator door into theworking space of the machine tool to carry out the necessary work.However, this also means that the other machine tools in the machinetool center can no longer be served by the loading device if the safetyof the operator is given priority.

In other words, as long as the operator is busy with one of the machinetools through the operator door the appliance cannot move the loadingdevice past this machine tool without endangering the operator.

SUMMARY OF THE INVENTION

In view of the above it is an object of the present invention to improvethe known machine tool center such that it can be better used with aless complicated construction whereby an increased work safety for theoperator and improved functional reliability of the machine tool are tobe achieved.

This object is achieved by the invention in that the loading device isarranged below the working space of the machine tool.

The object underlying the invention is thus achieved in full. Theinventors of the present application have namely recognized that theloading device can thus be mounted underneath the working surface of themachine tool, as it were, so that the operator door remains free forset-up and service work, repairs, etc. This further means that all othermachine tools in the new machine tool center can still be served by theloading device at no risk to the operator.

Since the loading device is arranged beneath the working space of themachine tool it is thus also automatically almost completely within theexternal contour, in other words the casing of the machine tool ormachine tool center, so that the necessary floor space required for themachine tool center is also reduced.

It is hereby preferred if the respective machine tool displays a loaderspace, in which the loading device is arranged preferably within acasing of the machine tool, in front of its respective machine standwhich supports a workpiece table arranged in the respective workingspace.

The advantage of this is that the loading device is on the one handarranged favorably in a space which either already exists in the machinetool or which can be provided with no great problem. Since the loadingdevice may be located within the machine tool's casing, this ensures aparticularly safe protection for the operator working on a machine toolpast which the loading device is moving to serve a machine tooldownstream from the machine tool which is, for example, being repaired.

It is furthermore preferred that the loader space is connected to therespective working space by a respective loading opening through whichthe loading device changes the workpieces.

This measure is particularly advantageous with respect to the functionalreliability of the machine tool center since the working space of therespective machine tool is not completely open to the loader space butis only connected to this via a loading opening so that any chipsproduced during machining of the workpiece, drilling water used, etc.only affects the loading device to a minor extent. If the loadingopening is designed and arranged in a geometrically favorable positionthis soiling of the loading device can be kept very small.

In a further embodiment it is however preferred if the loading openinghas a cover which is opened to change a workpiece.

This thus ensures complete protection of the loading device againstsoiling. The cover is only opened when a workpiece is changed, wherebythe machine tool itself is inoperative during this workpiece change sothat no dirt can pass through the open loading opening into the loaderspace. This measure thus also contributes to the functional reliabilityof the new machine tool center.

That is then further preferred that the cover is mechanically and/orelectrically/electronically locked when the operator door is open.

This measure further increases the work safety for the operator since itprevents the loading device entering the working space of a machine toolon which an operator is working, e.g. to change tools. This lock caneither be effected purely mechanically, so that when the operator dooris open a mechanical limit stop or similar prevents the process controlfrom releasing the cover for the loading opening. Further measures maypossibly be provided which prevent the loading device from attempting tochange a workpiece through a closed loading opening.

In the course of the progressive electrical/electronic control ofmachine tools it can also be provided that the control devices providedto open the cover are blocked by the process control as soon as theoperator door is opened.

It is generally preferred that the loading device display a loaderserving as a workpiece changer which moves longitudinally along a guiderail whose cross-section is preferably profiled.

This measure is advantageous with respect to the simple construction ofthe machine tool center since only one loader is required although anumber of different machine tools may be provided in a line or circle inthe new machine tool center. Although it would be possible to move theworkpieces in the loader space and to provide a workpiece changer forevery machine tool analogous to the tool changer, the concomitant costswould, however, be considerable.

It is hereby preferred if the loader displays a drive unit whichautomatically runs along the guide rail.

This measure is also advantageous from a constructional point of viewsince no chains, belts or similar facilities such as are otherwise oftenused in machine tools, are required to move the loader between themachine tools and loading/unloading station. The loader is thus aself-propelled workpiece changer, in a manner of speaking.

It is furthermore preferred that the loader display a swivel arm whichis retracted when the loader is moving, and which is at least partlyswiveled into the working space through the loading opening to changethe workpiece.

The advantage of this is that the loading device requires only a smallspace, the loader is folded away, as it were during movement so that theloading device can be arranged in a very small space beneath the workingspace of the machine tools.

In a further embodiment it is then preferred if a double gripper forworkpieces is arranged on the swivel arm.

The advantage of this measure is that the workpiece can be changed veryquickly, the double gripper namely grasps the workpiece which has justbeen finished and replaces this with a new workpiece to be processed inone movement, following which the swivel arm is retracted into theloader space. This very fast workpiece change leads to the furtheradvantage that more machine tools can be arranged alongside one anotherin the new machine tool center since the loading device can now servemore other machine tools within the machining time normally required byone of the machine tools to process the workpiece which has just beeninserted.

On the whole it is preferred that the workpieces are clamped inworkpiece holders which are fitted in fixture holders located in therespective working space of the respective machine tool.

This also advantageously increases the functional reliability of the newmachine tool center since the fixture holders and the loading deviceonly have to be designed to accommodate these workpiece holders so thatvarious workpieces can be processed with no set-up times.

It is further preferred that the loading/unloading station comprise aclamping station in which the workpieces are changed in the workpieceholders.

This measure is on the one hand advantageous from a constructional pointof view since the new machine tool center can now be operated fullyautomatically, as it were. A further advantage of this measure is thatthe new machine tool center only requires two workpiece holders morethan the number of machine tools in the machine tool center. One of theadditional workpiece holders is located in the clamping station and isfitted with a new workpiece whereas the second additional workpieceholder is in the loader and is exchanged with another workpiece holderwith finished workpiece in the machine tool.

It goes without saying that it is also possible to have workpiecesprocessed in sequence by various machine tools in the new machine toolcenter. The loading device then inserts, e.g., an unmachined workpieceinto a first machine tool and removes a finished workpiece, which isthen inserted into a second machine tool, whereby a workpiece which hasbeen subjected to two working cycles is then removed from this machine.This workpiece can then be exchanged in a third machine tool for aworkpiece which has already been processed in this third machine, etc.

Summing up, the advantages of the new machine tool center thus lie inthe fact that the loading device arranged beneath the working spaces canstill be operated if one or more machine tools are being serviced. Theloading device then moves beneath these machine tools which are atpresent inoperative and only serves the other machine tools in themachine tool center. Since the loading device is now arranged in theseparate loader space this also ensures the maximum possible work safetyfor the operator. The special design of the loader space and loadingdevice also ensure that the loading device is protected against thepenetration of dirt and only accesses the working space of a machinetool when the operator door is closed. This improves the work safety andalso the functional reliability of the loading device. The use ofworkpiece holders and a self-propellant workpiece changer alsoguarantees a rapid workpiece change with a relatively simpleconstruction and little use of material so that it is possible to selecta relatively high number of machine tools per machine tool center at lowcost.

It is hereby generally preferred that the cover display a flap cover,essentially vertical when closed, which is partly covered by anessentially horizontal running sliding cover.

The advantage of this is that through the combination of these twocovers the largest possible loading opening can be provided during aworkpiece change whereby the geometric arrangement of the sliding coverto the flap cover as mentioned ensures that no dirt penetrates theloading device when the cover is closed.

Further advantages can be derived from the description and encloseddrawing.

It is understood that the aforementioned features and those to beexplained in the following can be used not only in the specifiedcombinations but also in other combinations or alone without goingbeyond the scope of the present invention. One embodiment of theinvention is shown in the drawing and will be explained in more detailin the following description. In the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front view of the new machine tool center in detail;

FIG. 2 shows a section through the machine tool center from FIG. 1 alongline II--II, without loader in the loader space;

FIG. 3 shows a section along line III--III from FIG. 1 with a loader inposition and retracted swivel arm; and

FIG. 4 shows a representation as in FIG. 3, though with extended swivelarm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the front view of a machine tool center 10 in which themachine tools 11, 12 and 13 (only indicated) are arranged alongside oneanother. These machine tools 11, 12, 13 can either be arranged in astraight line or circle. A loading/unloading station 14 is provided inaddition to the machine tools 11, 12, 13.

The machine tools 11, 12, 13 display a casing 15 which completelysurrounds them and in which there is an operator door 16 for eachmachine tool 11, 12, 13 through which an operator has access to theworking space 17. Set-up and service work is carried out for theindividual machine tools 11, 12, 13 through this operator door 16.

A clamping station 18, shown only diagrammatically, is provided in theloading/unloading station 14 in which individual workpiece holders 19are provided with workpieces 21 to be processed. The workpiece holders19 provided with workpieces 21 in this manner are transported to theindividual machine tools 11, 12, 13 by means of a loading device 22 andinserted into the respective working space 17 and processed. Thefinished workpieces 21 are transported from the working spaces 17 backto the clamping station 18 in their workpiece holders 19 where they areexchanged for new workpieces 21 which are to be processed.

In FIG. 1 it can also be seen that there is operator console 23 at eachof the machine tools 11, 12, 13 and the loading/unloading station 14 viawhich the normal operator commands can be entered.

In accordance with the invention, the loading device 22 is arranged in aloader space 25 in the new machine tool center 10 from FIG. 1 which islocated beneath the working spaces 17 of the machine tools 11, 12, 13and preferably inside the casing 15. In this loader space 25 a loader 26moves back and forth along a guide rail 27 and hereby transports theworkpiece holder 19 containing workpieces 21 between the clampingstation 18 and the working spaces 17.

On account of the special arrangement of the loading device 22 theoperator doors 16 of the machine tools 11, 12, 13 are accessible tooperators at all times without these being endangered by the loader 26which may be passing by.

FIG. 2 shows a cross-section through the machine tool 12 as a detail ofa sectional view along line II--II from FIG. 1, whereby a spindle head29 is indicated which is provided to process the workpiece in theworking space 17.

The machine tool 12 comprises a machine base 31 on which adiagrammatically indicated workpiece table 32 is provided which in amanner of speaking fixes a working surface 33 in the working space 17. Afixture holder 34 is arranged on the workpiece table 32 which isdesigned to grip the workpiece holder 19 and hold this during processingby tools provided in the spindle head 29. In FIG. 2, 19' indicates aworkpiece holder holding a finished workpiece whereby the workpieceholder 19' is only diagrammatically indicated by a circle.

In FIG. 2 it can clearly be seen that in the representation showntherein the loader space 25 is arranged to the left of the machine base31 below the working space 17 and at least partly below the workingsurface 33. Furthermore, it can also be clearly seen that incross-sectional view the loader space 25 is arranged within the casing15.

The loader space 25 is connected to the working space 17 by a loadingopening 36. A cover 37 is hereby provided which is closed duringprocessing of the workpiece by tools in the working space 17 so that nodirt can enter the loader space 25.

The cover 37 is designed in two parts and comprises a sliding cover 38,which points upwards in FIG. 2 and is inclined towards the workingsurface 33, and a flap cover 39 which runs roughly vertical to theworking surface 33 and can be closed on this. It can be seen that thesliding cover 38 overlaps over the flap cover 39 so that splashing drillwater, flying workpiece chips, etc. cannot enter the loader space 25between the sliding cover 38 and flap cover 39.

The cover 37 is locked with the operator door 16 in such a way that thecover 37 can only be opened when the operator door 16 is closed, thoughthis is not shown in more detail in FIG. 2. In this way it is ensuredthat an operator working in the working space 17 on the machine tool 12cannot be injured by a sudden workpiece change. Moreover, if theoperator door 16 is open, suitable control measures ensure that theloader 26 passes by this machine tool and serves the next machine toolso that the failure of one machine tool in the machine tool center 10does not lead to the complete failure of the machine tool center. Thus,machine tools which are downstream, viewed from the loading/unloadingstation 14, from the machine tool which is currently being serviced canstill be supplied with new workpieces by the loading device 22.

FIG. 3 is a view similar to that in FIG. 2, though along line III--IIIfrom FIG. 1 showing the situation when the cover 37 is open and theloader 26 has entered the area beneath the working space 17, in thiscase of machine tool 11.

This loader 26 is a self-propellant workpiece changer 40, as it were,displaying a drive unit 41 with motor 42 on a guide rail 27 whichensures the mobility of the loader 26 along the guide rail, whosecross-section is preferably profiled, in a suitable manner.

The moveable workpiece changer 40 also displays a foldaway or slidingswivel arm 43 fixed to this which is retracted in FIG. 3 so that it islocated in the loader space 25. A pivoted double gripper 44 is arrangedon the top end of the swivel arm 43 which carries a workpiece holder inone hand whereas the other hand is still empty.

In FIG. 3 it can clearly be seen that the loader 26 is folded away in acompact manner in the position show so that the loader space 25 can bearranged in front of the machine base 31 and beneath the working space17 without the outer contour of the machine tool having to besignificantly changed.

In FIG. 3 a common trailing cable installation 45 can also be seen whichprovides electrical, pneumatic and possibly hydraulic connections 46 forthe loader 26 and connects this via the connections 46 to thecorresponding control unit/operator console 23.

In FIG. 3 a workpiece table 47 can also be recognized behind the flapcover 37 which can have, e.g. an abutment so that clamped workpieces canbe centered better.

In the representation in FIG. 4, which otherwise corresponds to FIG. 3,the swivel arm 43 has been pivoted or extended through the loadingopening 36 into the working space 17 where the double gripper 44 hasalready gripped the workpiece holder 19', bearing a workpiece which hasalready been processed by the machine tool 11. The workpiece holder 19and workpiece holder 19' are now exchanged through a swivel movementaround 180° in the plane of FIG. 4 so that the fixture holder 34 whichcan be seen in FIG. 2 can accept the workpiece holder 19 with the as yetunprocessed workpiece. The swivel arm 43 is then folded away orretracted so that the position shown in FIG. 3 is assumed.

Finally, the cover 37 is closed so that the new workpiece can beprocessed in the working space 17 in the machine tool 11 whilst theloader 26 brings the workpiece holder 19' to the loading/unloadingstation 18 and exchanges this for a workpiece holder 19 which has beenprovided with a workpiece still to be processed in the clamping station18.

What I claim is:
 1. A machine tool center, comprising:at least onemachine tool each having a casing and a working area for processingworkpieces and accessible through an operator door; a loading/unloadingstation for the workpieces; a loader space which is arranged within thecasing and below the working area of the respective machine tool, saidloader space being connected to the working area by a loading opening,the loading opening comprising a cover which is opened to change aworkpiece; and a loading device for transporting the workpieces betweenthe loading/unloading station and the respective machine tool and forchanging the workpieces at the respective machine tool, said loadingdevice being arranged within the loader space; wherein the loadingdevice is arranged in front of a respective machine stand which supportsa workpiece table arranged in the respective working area, theworkpieces are clamped in workpiece holders which are fitted in fixtureholders located in the respective working area of the respective machinetool, and the loading/unloading station comprises a clamping station inwhich the workpieces are exchanged in the workpiece holders.
 2. Themachine tool center of claim 1, wherein the loading device comprises aloader serving as a workpiece changer which moves longitudinally along aguide rail.
 3. The machine tool center of claim 2, wherein the loadercomprises a drive unit which automatically runs along the guide rail. 4.The machine tool center of claim 3, wherein the loader comprises an armwhich is retracted when the loader is moving, and which is at leastpartly moved into the working space through the loading opening tochange the workpiece.
 5. The machine tool center of claim 4, wherein adouble gripper for workpieces is arranged on the arm.
 6. The machinetool center of claim 4, wherein the arm is a swivel arm that is swiveledinto the working space.